Touchscreen not responding intermittently: a software/firmware issue?

Hi.

I have been using this iPhone for about a year now, after it was given to me by my mom who used it before. Now, I come before this problem of me randomly losing touchscreen responds, and I immediately contacted Apple Support. Now, this is something that first happened three days ago, and I first suspected of hardware issues or a heat issue, but both were not the case. I haven’t checked it in with an Apple Authorized Service Provider (my country doesn’t have an Apple Store) (I might go within next week or so). Now, I suspect either a firmware issue, or an app issue, and it’s more likely towards the former.

Why do I suspect this? I looked at my phone (which after locking, can’t be unlocked until you force restart it a couple of times) and I saw that every time I force restart it, I cant force touch the camera in the lower right side. In fact, that button is darkened out, while the flashlight button is when I cant use the screen. Another thing is that the Face ID is unusable (I look at the camera, but it doesn’t respond to my face). One more thing to notice is the sudden “green flash” of the OLED before the Apple logo appears.

Does other Apple users experience the same issue here? Or is it just me? Please let my know here.